package com.lagou.sqlSession;


import com.lagou.config.BoundSql;
import com.lagou.pojo.Configuration;
import com.lagou.pojo.MappedStatement;
import com.lagou.utils.GenericTokenParser;
import com.lagou.utils.ParameterMapping;
import com.lagou.utils.ParameterMappingTokenHandler;

import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.net.URLDecoder;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.util.ArrayList;
import java.util.List;

/**
 * @author wangcw
 */
public class SimpleExecutor implements  Executor {


    private PreparedStatement preparedStatement;


    @Override
    public <E> List<E> query(Configuration configuration, MappedStatement mappedStatement, Object... params) throws Exception {
        inputPreparedStatement(configuration,mappedStatement,params);
        ResultSet resultSet = preparedStatement.executeQuery();
        String resultType = mappedStatement.getResultType();
        Class<?> resultTypeClass = getClassType(resultType);
        ArrayList<Object> objects = new ArrayList<>();
        while (resultSet.next()){
            Object o =resultTypeClass.newInstance();
            ResultSetMetaData metaData = resultSet.getMetaData();
            for (int i = 1; i <= metaData.getColumnCount(); i++) {
                String columnName = metaData.getColumnName(i);
                Object value = resultSet.getObject(columnName);
                PropertyDescriptor propertyDescriptor = new PropertyDescriptor(columnName, resultTypeClass);
                Method writeMethod = propertyDescriptor.getWriteMethod();
                writeMethod.invoke(o,value);
            }
            objects.add(o);
        }
        return (List<E>) objects;
    }

    @Override
    public void insert(Configuration configuration, MappedStatement mappedStatement, Object... params) throws Exception {
        inputPreparedStatement(configuration,mappedStatement,params);
        preparedStatement.execute();
    }


    @Override
    public Integer update(Configuration configuration, MappedStatement mappedStatement, Object... params) throws Exception {
        inputPreparedStatement(configuration,mappedStatement,params);
        return  preparedStatement.executeUpdate();
    }

    @Override
    public Integer delete(Configuration configuration, MappedStatement mappedStatement, Object... params) throws Exception {
        inputPreparedStatement(configuration,mappedStatement,params);
        return preparedStatement.executeUpdate();
    }

    /**
     * 注入参数和sql
     */
    private void inputPreparedStatement(Configuration configuration, MappedStatement mappedStatement, Object... params) throws Exception {
        BoundSql boundSql = getBoundSql(mappedStatement.getSql());
        preparedStatement = configuration.getDataSource().getConnection().prepareStatement(boundSql.getSqlText());
        String paramterType = mappedStatement.getParamterType();
        Class<?> paramtertypeClass = getClassType(paramterType);
        if ("java.lang".equals(paramtertypeClass.getPackage().getName())){
            preparedStatement.setObject(1,params[0]);
            return;
        }
        List<ParameterMapping> parameterMappingList = getBoundSql(mappedStatement.getSql()).getParameterMappingList();
        for (int i = 0; i < parameterMappingList.size(); i++) {
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();
            //反射
            Field declaredField = paramtertypeClass.getDeclaredField(content);
            //暴力访问
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);
            if (o instanceof String){
                o = URLDecoder.decode(o.toString(), "utf-8");
            }
            preparedStatement.setObject(i+1,o);
        }
    }

    private Class<?> getClassType(String paramterType) throws ClassNotFoundException {
        if(paramterType!=null){
            Class<?> aClass = Class.forName(paramterType);
            return aClass;
        }
         return null;

    }


    /**
     * 完成对#{}的解析工作：1.将#{}使用？进行代替，2.解析出#{}里面的值进行存储
     * @param sql
     * @return
     */
    private BoundSql getBoundSql(String sql) {
        //标记处理类：配置标记解析器来完成对占位符的解析处理工作
        ParameterMappingTokenHandler parameterMappingTokenHandler = new ParameterMappingTokenHandler();
        GenericTokenParser genericTokenParser = new GenericTokenParser("#{", "}", parameterMappingTokenHandler);
        //解析出来的sql
        String parseSql = genericTokenParser.parse(sql);
        //#{}里面解析出来的参数名称
        List<ParameterMapping> parameterMappings = parameterMappingTokenHandler.getParameterMappings();

        BoundSql boundSql = new BoundSql(parseSql,parameterMappings);
         return boundSql;

    }


}
